Cathodic Deposition Research Articles

Electrochemistry of Uranium on Liquid Cadmium Electrode in LiCl-KCl Eutectic

This work presents the electrochemical study of LiCl-KCl-UCl3 solutions at the temperature range 673–823 K on inert and reactive electrodes, i.e. W and Cd, respectively. On inert electrode, U(III) ions were reduced to metallic uranium through one step and the mechanism of the cathode reaction was irreversible. The diffusion coefficients of U(III) ions in molten chloride eutectic and liquid cadmium were calculated. On reactive electrode, U(III) ions were reduced with depolarization and were accompanied by the formation of intermetallic compound UCd11. The reactions of the cathodic deposition and anodic dissolution of the U-Cd alloy were studied and the conditions of the alloy formation via galvanostatic electrolysis were found. The solubility and the activity of uranium in liquid cadmium were determined.

The Effects of Temperature and Lithium Polysulfides on the Composition of Lithium Cathodic Deposits Formed at a Steel Electrode

The Effects of Temperature and Lithium Polysulfides on the Composition of Lithium Cathodic Deposits Formed at a Steel Electrode

The Influence of Nitrogen Partial Pressure on the Microstructure and Mechanical Properties of HfNbTaTiVZr High-Entropy Nitride Coating Deposited via Direct Current Cathodic Vacuum Arc Deposition

In recent years, high-entropy alloys have attracted increasing scientific interest. Due to their promising combination of properties, such as high hardness and high temperature stability, they are attractive for use as tool coatings for machining applications, to give but one example. Previous studies often focused on layer deposition using magnetron sputtering. Comparatively little research has been carried out to date on coating deposition using direct current cathodic vacuum arc deposition (CAE), with higher achievable rates and almost completely ionized plasmas. The aim of this work is to investigate (HfNbTaTiZr)N-coatings produced by CAE. The nitrogen content was varied and the effects on the coating properties were investigated. Changing the N2/(N2 + Ar) ratio between 0.1 and 1.0 and varying the working pressure in the chamber from 2 Pa to 5 Pa resulted in variations of the nitrogen content of the coatings, ranging from 30 at% to 50 at%. Although different microstructures of the coatings were obtained, there was only a minor influence on the hardness and Young’s modulus.

Sustainable super-hard and thick nanodiamond composite film deposited on cemented carbide substrates with an interfacial Al-interlayer

Super-hard nanodiamond composite (NDC) films, synthesized via cathodic arc plasma deposition on unheated WC − Co substrates, offer an eco-friendly solution for cutting tools. A 100 nm-thick Al-interlayer mitigates Co catalytic effects, improving adhesion and yielding smooth and dense 10 µm-thick films at a deposition rate of 3.3 μm/hr. These grain-boundary-rich nanostructured films, with an impressive 58 GPa hardness attributed to a substantial 70 % C sp3 fraction, prove optimal for hard coatings. The Al-interlayer effectively suppresses Co catalytic effects, forming a dense Al-oxide layer, enhancing film hardness and adhesion (Lcr = 18.6 N). NDC films present a promising eco-friendly option for high-performance hard coatings.

Improved corrosion resistance and biocompatibility of magnesium implants by cathode-deposited polypyrrole/dicalcium phosphate dihydrate composite coating

As a new-generation of concerned biomedical metal implants, magnesium (Mg) alloy has the degradability, biocompatibility and mechanical properties close to human bones that inert metals do not have. However, the side effects caused by rapid degradation become the biggest obstacle restricting its practical application. Here, we report that the preparation of polypyrrole/calcium phosphate (PPy/CaP) composite coating on Mg alloy by the application of the cathode deposition twice in a row, which delayed the corrosion of Mg alloy and reduced its corrosion current density, the biocompatibility was also greatly improved. This method is simple to operate, and could get a tightly bonded PPy coating on active metals without passivation treatments. It also avoids the substrate exposure due to the high solubility of the single electrodeposited calcium phosphate coating, and finds the future direction for application of electrodeposited modified Mg alloy.

Novel Additives in Copper Electrorefining-Small Laboratory Scale.

This research aimed to evaluate the effectiveness of new organic substances, including a novel ionic liquid based on polyhexamethylenebiguanidine, polyhexamethyleneguanidine, and safranin in the copper electrorefining process. Experiments were conducted on a small laboratory scale using industrial copper anodes. Single doses of new additives did not improve process indicators (current efficiency, average cell voltage, specific energy consumption) or the quality of copper cathode deposits. However, a combination of a new ionic liquid based on polyhexamethylenebiguanidine and thiourea resulted in a satisfactory current efficiency of 97%, an average cell voltage of 0.110 V, a low specific energy consumption index of approximately 100 kWh/tCu, and smooth cathode surfaces. These results were superior to those obtained with industrial additives (bone glue and thiourea). The findings enhance our understanding of how these substances influence the electrorefining process and suggest the potential for more efficient and sustainable methods. Further research is recommended to validate these findings and explore their industrial applications.

Electrochemical Activity Measurements of UCl3 in Molten NaCl-MgCl2-UCl3

Abstract Open circuit potential (OCP) measurements were made to determine uranium chloride (UClx) species activity in NaCl–MgCl2, which is a candidate salt for use in a molten salt reactor fuel. The operating temperature ranged from 500 to 650 °C, and the measurement system used a U-Zr working electrode (WE) and Ag/AgCl reference electrode (RE). The activity was calculated to range from 2.52×10−6 to 2.99×10−8 (with uncertainties of ±1.0×10−7 and ±1.1×10−9, respectively), dependent upon the temperature and concentration of UCl3 (ranging from 0.25 to 11.55 wt.%). Fit of the OCP data to the Nernst equation resulted in values of 3.1 to 4.8 electrons transferred per U atom. This indicates the possibility for codeposition of Mg2+ and U3+ under certain conditions. Scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photo-electron spectroscopy analyses of cathodic deposits confirm the presence of metallic magnesium.

Effect of ultrasound assistance on the mechanical performance and corrosion resistance of Zn-Ni coatings produced by cathode plasma electrolysis deposition

Zn-Ni coatings were fabricated via ultrasonic-assisted cathodic plasma electrolysis deposition (US-CPED) technology. The results demonstrate that ultrasonic assistance can significantly affect the deposition and growth process of Zn-Ni coatings, which is attributed to ultrasonic vibration reducing the diameter of bubbles and inducing a more uniform distribution of the vapor gaseous envelope (VGE) on the surface of the substrate. The Zn-Ni coatings with more homogeneous microstructure were formed due to the more uniform plasma discharge process on the surface of the substrate based on the VGE uniform distribution. Compared to the Zn-Ni coatings without ultrasonic assistance, the thickness and roughness of Zn-Ni coatings with ultrasonic assistance increased by >80 % and decreased by over 40 %, respectively. Better Zn-Ni coating quality brings higher corrosion resistance. In addition, ultrasound can accelerate the iteration of bubbles in VGE to enhance the work-hardening effect, improving the mechanical properties of the Zn-Ni coatings. This work introduces a novel insight into the controllability of the CPED process and paves the way for exploring other methods to stabilize the CPED process.

On the formation of dendritic iron from alkaline electrochemical reduction of iron oxide prepared for metal fuel applications

Low-temperature electrochemical reduction (electroreduction) of iron oxides is a promising alternative to the conventional methods for iron production due to its CO2-free operation and relatively low energy consumption. In this work, we demonstrate a novel approach for electrochemical iron production by promoting the formation of dendritic structures during iron electrodeposition, which facilitates the easy harvesting of deposits in powder form. Experiments were conducted using a single pair of parallel plate electrodes, immersed in a mixture of hematite (Fe2O3) powder and aqueous alkaline (NaOH) slurry. The effects of current density, Fe2O3 mass fraction, temperature, and powder size on current efficiency and deposit morphology are investigated. A large quantity of dendritic iron structures is observed when experiments are carried out without stirring and/or applying heat from a heating plate. This condition suggests temperature and (ion/species) concentration gradients in the system. The dendrites are mainly deposited on the cathode's sides, corners, and edges. Different deposits and dendritic structures (compact layer deposit, moss-like deposit, deposit with whisker-like dendrites, and deposit with crystal-like dendrites) are observed as operating conditions change. Overall, a cathodic deposition of metallic iron with a high Faradaic efficiency (≥90 %) is successfully accomplished. The present findings provide new insights into the production of electrolytic iron powder and its future use as a carbon neutral and sustainable fuel/energy carrier.

Electrochemical diagrams showing equilibrium cathodic phases and their compositions as function of electrolyte composition and type of alloy phase diagram

In this paper the dependence of the elemental and phase compositions of the binary A-B cathodic deposits are computed by constructing “Electrochemical Diagrams”, abbreviated as ECDs, which potentially have a high practical significance. An ECD shows phases and compositions of cathodic alloy products as function of electrolyte composition at fixed temperature, pressure and at low current density upon galvano-static electrochemical co-deposition of components A-B from the same electrolyte on an inert cathode. The following rules are established here to construct the ECDs for binary A-B alloys: i). among all possible cathodic phases the one will be electrodeposited that provides the least negative cathodic deposition potential, ii). two or three (but not four or more) phases can be co-deposited on the cathode if their equilibrium cathodic potentials are equal and are the least negative among all possible cathodic phases, iii). the equilibrium compositions of solid and liquid A-B alloys that form on the cathode can be found from the condition of equality of the partial equilibrium cathodic potentials of components A and B. Based on the above three rules, ECDs are constructed for some basic types of binary equilibrium alloy phase diagrams with the composition of the alloy on its y-axes as function of the ionic composition of the electrolyte on its x-axes. In all cases the clear connection is shown between the ECDs and their corresponding alloy phase diagrams. The following geometric features are established for ECDs: i). solution phases are characterized by continuous curves, ii). phases of fixed compositions are characterized by horizontal lines, iii). two-phase mixtures are characterized by vertical lines, iv). three-phase equilibria are characterized by single points along the vertical lines corresponding to the two-phase equilibria of the parent phases of the third phase. It is shown that the restricted phase rule of Gibbs (= the maximum number of coexisting phases = the number of independent components + 1) is valid also for the ECDs. As examples, ECDs are calculated for the Ni-Co system and for the Ti-B system and good agreement is found between these calculated diagrams and the experimental data.

Evaluation of Upscaling the Selective Electrophoretic Deposition of Reduced Graphene Oxide on Miniaturized Au Interdigital Electrodes from Chip-to Wafer-Level

Today’s novel materials challenge the research industry to enhance the performance and to reduce the power consumption of microchips as well as to develop new sensor principles. All this applies pressure on the investigation of new economical mass production technologies for the integration into standard process sequences or on top of state-of-the-art CMOS devices. Since the discovery of graphene in 2004, many different variations have been investigated, thus the number of publications of graphene-based content grew from a few in 2004 exponential to 1.2 million only in 2019, according to Google Scholar analysis. The deposition of graphene-based materials at wafer-level is still difficult to do economically on standard SEMI wafers up to 8” diameter. In this publication, the selective electrophoretic deposition (EPD) of reduced graphene oxide flakes (rGO) will be shown. This technique is a very promising deposition method for large scale fabrication. The EPD of rGO particles is the only known way to create 3D surface topologies for an enhanced sensing area of electrochemical sensor applications e.g. biosensors. The electrical and chemical properties of this novel material provides a broad range of applications for possible sensor solutions [1, 2]. Firstly, the deposition will be shown on chip scale to gain optimum parameters in suspension preparation and EPD deposition time/voltage for a uniform particle deposition over the sensor area. Shortcuts from particles between the transmission lines or co-deposition on reference electrodes have to be avoided. This leads to a high selectivity in rGO particle deposition on Au-structures. Afterwards designs and experiments have been made on array level and a proof of concept wafer-level deposition with a low volume suspension is demonstrated. In previous work, the adhesion of rGO on Au structures in electrochemical sensors with a liquid flow, showed a migration of the deposited particles with the friction of the liquid [3]. Therefore, standard separation of particle agglomeration or splitting of primary particles with ultra sonic sonotrodes are not sufficient to gain highly concentrated suspensions with homogenous target particle distributions (< 0,5µm ≤ 1µm ≥ 5µm). For this reason, a novel particle crushing preparation by ball milling is introduced and enhanced selectivity with an improved adhesion is demonstrated. A full process of the preparation of the colloidal suspension with the definition of target particle sizes with an optimum zeta potential will be provided and the cathodic electrophoretic deposition shown [4, 5]. For the evaluation of the deposition experiments, stereo microscopy is used to reveal the selectivity on the interdigital electrode (IDE) structures (sensor area) and scanning electron microscopy (SEM) analysis is used to characterize particle sizes and 3D topography, in terms of primary and secondary particles (agglomerates). For this study, IDE structures with 15 different geometry variations (3µm to 15µm lines and spaces) are used that were manufactured [6] to evaluate the rGO deposition on chip level. A novel multisensory array design with eight sensing areas are presented, combined with wafer-level deposition as a proof of concept on a 200mm wafer.

A Comprehensive Review of Cathodic Arc Evaporation Physical Vapour Deposition (CAE-PVD) Coatings for Enhanced Tribological Performance

In the realm of industries focused on tribology, such as the machining industry, among others, the primary objective has been tribological performance enhancement, given its substantial impact on production cost. Amid the variety of tribological enhancement techniques, cathodic arc evaporation physical vapour deposition (CAE-PVD) coatings have emerged as a promising solution offering both tribological performance enhancement and cost-effectiveness. This review article aims to systematically present the subject of CAE-PVD coatings in light of the tribological performance enhancement. It commences with a comprehensive discussion on substrate preparation, emphasizing the significant effect of substrate roughness on the coating properties and the ensuing tribological performance. The literature analysis conducted revealed that optimum tribological performance could be achieved with an average roughness (Ra) of 0.1 µm. Subsequently, the article explores the CAE-PVD process and the coating’s microstructural evolution with emphasis on advances in macroparticles (MPs) formation and reduction. Further discussions are provided on the characterization of the coatings’ microstructural, mechanical, electrochemical and tribological properties. Most importantly, crucial analytical discussions highlighting the impact of deposition parameters namely: arc current, temperature and substrate bias on the coating properties are also provided. The examination of the analyzed literature revealed that the optimum tribological performance can be attained with a 70 to 100 A arc current, a substrate bias ranging from −100 to −200 V and a deposition temperature exceeding 300 °C. The article further explores advancements in coating doping, monolayer and multilayer coating architectures of CAE-PVD coatings. Finally, invaluable recommendations for future exploration by prospective researchers to further enrich the field of study are also provided.

Radiochemical and chemical characterization of fuel, salt, and deposit from the electrorefining of irradiated U-6 wt% Zr in hot cells

Abstract Metal fuels are considered as the promising candidates for future fast breeder reactors. Pyro-chemical reprocessing is the ideal method for reprocessing spent metallic fuels due to the inherent process advantages. Electrorefining run was demonstrated in a hot cell facility with irradiated U-6 wt% Zr alloy at 500 °C using LiCl–KCl eutectic melt. In order to understand the behavior of the actinides and various fission products during high-temperature electrolysis, various process streams, viz., irradiated metal alloy fuel, the eutectic salt, and the cathode deposit were analyzed for the uranium, plutonium, and other fission product contents. Various methods employed for characterizing the process streams and the behaviors of some of the fission products during the electrolysis process are highlighted. The major gamma emitting radionuclides present in the irradiated fuel were 106Ru, 125Sb, 134Cs, 137Cs, 144Ce, and 154Eu. During electrorefining, cesium, cerium and europium were oxidized and dissolved in the molten media, whereas ruthenium and antimony remained in the anode basket. A minor contamination of zirconium was found in the cathode deposit.

Cathodic deposition voltage-dependent properties of electrodeposited stoichiometric CdSe thin films for solar energy application

Cadmium Selenide thin films have been deposited on glass/fluorine-doped thin oxide substrate using a simple potentiostatic two-electrode electrodeposition configuration. The results of the structural analysis showed that CdSe is nanocrystalline with a cubic zinc blend structure. The energy band gap values of as-deposited CdSe thin films were found to (2.02–1.69) eV, while those of the annealed films (1.95–1.66) eV as the deposition voltage increased from (1935–1970) mV. These films have n-type conductivity for both as-deposited and annealed samples. Surface morphology analysis showed that the glass substrate was covered well by CdSe thin films. The average surface roughness of CdSe thin films changed with voltage in the range of (39.0–75.0) nm for as-deposited films and (43.2–77.0) nm for the annealed films. The elemental composition analysis confirmed that both Cd and Se were present, and stoichiometric composition was observed at 1950 mV.

Facilely Fabricated Zero-Bias Silicon-Based Plasmonic Photodetector in the Near-Infrared Region with a Schottky Barrier Properly Controlled by Nanoalloys.

Plasmonic Schottky devices have attracted considerable attention for use in practical applications based on photoelectric conversion, because they enable light to be harvested below the bandgap of semiconductors. In particular, silicon-based (Si) plasmonic Schottky devices have great potential for useful photodetection in the near-infrared region. However, the internal quantum efficiency (IQE) values of previously reported devices are low because the Schottky barrier is excessively high. Here, we are the first to develop AuAg nanoalloy-n-type Si plasmonic Schottky devices by cathodic arc plasma deposition. Interestingly, it is found that a novel nanostructure, which leads to the improvement of responsivities, is formed. Moreover, these plasmonic nanostructures can be fabricated in only ∼1 min. The fabricated AuAg nanoparticle-film structure enables proper control of the Schottky barrier height and increases the area of the Schottky interface for electron transfer. As a result, the considerably enhanced IQE of our device at a telecommunication wavelength of 1310 nm (1550 nm) without external bias is 4.6 (6.5) times higher than those in previous reports, and these responsivities are a record high. This approach can be applied to realize efficient photodetection in the NIR region and extend the use of light below the bandgap of semiconductors. This paves the way for future application advancements in a variety of fields, including photodetection, imaging, photovoltaics, and photochemistry.

Formation Processes of a Solid Electrolyte Interphase at a Silicon/Sulfide Electrolyte Interface in a Model All-Solid-State Li-Ion Battery.

Understanding the electrochemical reactions at the interface between a Si anode and a solid sulfide electrolyte is essential in improving the cycle stabilities of Si anodes in all-solid-state batteries (ASSBs). Highly dense Si films with very low roughnesses of <1 nm were fabricated at room temperature via cathodic arc plasma deposition, which led to the formation of a Si/sulfide electrolyte model interface. Li (de)alloying through the model interface hardly occurred during the first cycle, whereas it proceeded stably in subsequent cycles. Hard X-ray photoelectron spectroscopy and neutron reflectometry directly revealed that the reduction or oxidation of the interfacial component or Li3PS4 electrolyte occurred during the first cycle. Consequently, an interfacial layer with a thickness of 13 nm and primarily composed of Li2S, SiS2, and P2S5 glasses was formed during the first cycle. The interfacial layer acted as a Li-conductive, electron-insulating solid electrolyte interphase (SEI) that provided reversible (de)lithiation. Our model interface directly demonstrates the electrochemical reaction processes at the Si/Li3PS4 interface and provides insights into the structures and electrochemical properties of SEIs to activate the (de)lithiation of Si anodes using a sulfide electrolyte.

Site-specific metal-support interaction to switch the activity of Ir single atoms for oxygen evolution reaction

The metal-support interactions (MSI) could greatly determine the electronic properties of single-atom catalysts, thus affecting the catalytic performance. However, the typical approach to regulating MSI usually suffers from interference of the variation of supports or sacrificing the stability of catalysts. Here, we effectively regulate the site-specific MSI of Ir single atoms anchored on Ni layered double hydroxide through an electrochemical deposition strategy. Cathodic deposition drives Ir atoms to locate at three-fold facial center cubic hollow sites with strong MSI, while anodic deposition drives Ir atoms to deposit onto oxygen vacancy sites with weak MSI. The mass activity and intrinsic activity of Ir single-atom catalysts with strong MSI towards oxygen evolution reaction are 19.5 and 5.2 times that with weak MSI, respectively. Mechanism study reveals that the strong MSI between Ir atoms and the support stimulates the activity of Ir sites by inducing the switch of active sites from Ni sites to Ir sites and optimizes the adsorption strength of intermediates, thereby enhancing the activity.

Improved surface properties of AISI-420 steel by Ti[sbnd]C based coating using graphite cathodic cage with titanium lid in plasma deposition

In this work, titanium‑carbon (TiC) based coating is deposited on AISI-420 martensite stainless steel samples to improve surface properties. The coating is deposited using a graphite cathodic cage equipped with a titanium lid, which acts as a source of carbon and titanium. The hardness of samples (untreated hardness of 220 HV0.25) is increased up to 1337 HV0.25 and 1524 HV0.25 by coating deposition at cathodic (base plate connected with cathodic cage) and floating potential (with no external potential). The sample treated at cathodic potential exhibits expanded martensitic phase due to diffusion of carbon atoms. In contrast, additional TiC and chromium carbide Cr23C6 peaks are formed while treated at floating potential. The thickness of carburizing layer is 80 and 77 μm, when the coating is deposited at cathodic and floating potential, respectively. The wear volume of the untreated sample (1200 × 10−4 mm3) is reduced to ∼ (20 × 10−4 mm3) after the coating deposition, and the friction coefficient is also reduced due to the coating deposition. A significant decrease in corrosion rate is also observed, specifically at floating potential. It suggests that Ti-C-based coating using this modified cathodic cage plasma deposition (CCPD) is beneficial for the hardness, wear, and corrosion resistance of AISI-420 steel.

Cathodic electrophoretic deposition (EPD) of two-dimensional colloidal Ni(OH)2 and NiO nanosheets on carbon fibers (CF) for binder-free structural solid-state hybrid supercapacitor

The exponential growth of the renewable energies field and the increase of portable electric vehicles (EVs) demand a new generation of multifunctional efficient electrochemical energy storage devices (EESDs). In this work, binder-free hybrid battery-like electrodes were prepared by cathodic electrophoretic deposition (EPD). One-step (synthesis and deposition) processing of β-Ni(OH)2 was developed avoiding a previous calcination step to form NiO. The redox reaction (RR) contribution to the electrochemical performance of the hybrid electrodes was enhanced without influencing the mechanical properties of the CF substrate. Moreover, the sintering of the coated-CF under a high-vacuum atmosphere and the controlled mass deposition (<0.1 mg·cm−2) demonstrated to enhance the synergic effect of the redox reactions, ion diffusion (NiO) and the electrochemical double layer (CF) contributions. Thus, the hybrid electrodes in a half-cell configuration achieved remarkably high capacitance values (1161 F·g−1 at 2 A·g−1), while hybrid electrodes in a symmetric structural hybrid solid-state supercapacitor (HSSS) with an ionic liquid/resin structural solid-electrolyte reached a capacitance of 9.8 mF·g−1, a power and energy density of 3.5 mW·kg−1 and 1 mWh·kg−1 respectively and good electrochemical stability with a Columbic efficiency of 75 % at 0.8 mA·g−1.

High temperature decomposition and age hardening of single-phase wurtzite Ti1−xAlxN thin films grown by cathodic arc deposition

Wurtzite TmAlN (Tm=transition metal) themselves are of interest as semiconductors with tunable band gap, insulating motifs to superconductors, and piezoelectric crystals. Characterization of wurtzite TmAlN is challenging because of the difficulty to synthesize them as single-phase solid solution and such thermodynamic, elastic properties, and high temperature behavior of wurtzite Ti1−xAlxN is unknown. Here, we investigated the high temperature decomposition behavior of wurtzite Ti1−xAlxN films using experimental methods combined with first-principles calculations. We have developed a method to grow single-phase metastable wurtzite Ti1−xAlxN (x=0.65, 0.75, 085, and 0.95) solid-solution films by cathodic arc deposition using low duty-cycle pulsed substrate-bias voltage. We report the full elasticity tensor for wurtzite Ti1−xAlxN as a function of Al content and predict a phase diagram including a miscibility gap and spinodals for both cubic and wurtzite Ti1−xAlxN. Complementary high-resolution scanning transmission electron microscopy and chemical mapping demonstrate decomposition of the films after high temperature annealing (950∘C), which resulted in nanoscale chemical compositional modulations containing Ti-rich and Al-rich regions with coherent or semicoherent interfaces. This spinodal decomposition of the wurtzite film causes age hardening of 1–2 GPa. Published by the American Physical Society 2024